Transcript Chapter 5 Local Area Network Concepts and Architecture

Chapter 5
Local Area Network
Concepts and Architecture
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Network Fundamentals
Local Area Network (LAN)
Open Systems Interconnection (OSI)
LAN Architectures
Network Fundamentals
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Definitions
Classifications
Network topology
Network types
Local Area Network
Definition
• Network
• Backbond network
Classification
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Topology
Ownership
Geography
Transmission
Network Topology
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Star
Hierarchical
Mesh
Bus
Ring
Hybrid
Star Network
• Usage
– Centralized processing or communication
• Pros
– Expansion
– Implementation
– No limit to no. and length of arms
• Cons
– Single point of failure
– Overload of mater during peak traffic
Hierarchical Network
• Usage
– Distributed processing
• Tree structure with a root
• pro
– No single point of failure
Mesh Network
• Web structure
• Usage
– Public telephone system
• Pro
– Alternative communication route
• Con
– Line cost
Bus Network
• Usage
– Date entry or office environment
• Pros
– Independent between nodes
– High reliability
• Cons
– Limited number of attached device
– Hard to locate the problems
Ring Network
• Usage
– Manufacturing
• Pros
– Less attenuation
– Error control
– Network management
• Cons
– Failing of a node
Hybrid Networks
• Usage
– Connecting different networks
• Pro
– Communication between networks
• Con
– Conversion device and costs
– Compatibility
Network Ownership
• Private networks
• Public networks
• Valued added networks
Private networks
• Full control
• Special needs
• Expense
Public networks
• Controlled by carriers
• Regulated by government
• Inexpensive
Valued Added Networks
• Functions
– Code translation
– Speed conversion
– Store message and delivery
• Examples
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Telex
SWIFT
SITA (airline)
IVAN (insurance)
Networks by Geography
• Wide area network (WAN)
• Metropolitan area network (MAN): 30
miles
• Local area network (LAN): 5 miles
LAN Characteristics
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Limited distance within a few miles
High data rate - 2 to 1000Mbps
Low error rate
Good response time
Private owned
No regulation
Share hardware, software, and data files
Business Needs
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Corporate asset for competitive edge
Data accessibility (information distribution)
Less expenses
Better service - response time and reliability
Higher productivity
Control or secure
LAN Analysis & Design
• Meet business objectives (strategic
planning)
• Prevent technological obsolescence
LAN Hardware & Software
• Hardware
– PC: servers and clients
– Network interface card (NIC): physical address
– Media or Cables
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Unshielded twisted pair (inexpensive)
Coaxial cable (faster, expensive)
Optical fiber (fastest, expensive)
Air for wireless
– Hub (compatible)
• connect wires and cables, repeater, error detection
• Software: network operating system
Open System Interconnection Model
• International Standards Organization
• Interconnection of dissimilar network
• Seven Layers
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Application
Presentation
Session
Transport
Network
Data Link
Physical
Application Layer
• Utilities support end-user application
program
• Determine data to be send at originating end
• Process data at receiving end
Presentation Layer
• Change data format
• Compression/expansion
• Encryption/decryption
Session Layer
• Communication rules of machines or
application programs
• Accounting functions
Transport Layer
• Identify receiving address
• Flow control: rate of transmission
• Recovery: calculate and check checksum of
entire message
Network Layer
• Route message
• Dissemble and assemble data (packets)
• Accounting functions
Data Link Layer
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By IEEE 802
Establish link between two ends
Detect and correct transmission error
Add header and trailer
Divide data unit for transmission (frames)
Sublayers
– Media access control (MAC): token ring or
Ethernet
– Logical link control (LLC): assembling and
disassembling frames, error control, flow
control
Physical Layer
• Electrical, mechanical, procedural
specifications for data transmission
• Hardware specification by RS-232-C
Other Concepts
• Protocol
• Encapsulation/ de-encapsulation
Standards
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IEEE 802.2: LLC protocol
IEEE 802.3: CSMA/CD baseband bus
IEEE 802.4: token passing bus
IEEE 802.5 token passing ring
Fiber Distributed Data Interface (FDDI)
Standard
LAN Architecture Model
• Network architecture includes
– Access methodology
– Logical topology
– Physical topology
• Network configuration includes
– Network architecture
– Media choice
Access Methods
• Contention: carrier sense multiple access
with collision detection (CSMA/CD)
– Inexpensive NIC
– For: office application
– Not for: manufacturing due to inconsistent
response time
• Token passing: 24 bits of token (free or
busy)
– More efficient at higher network utilization rate
– More expensive NIC
– Supported by IBM
Topology
• Logical
– Sequential
– Broadcast
• Physical
– Bus: line broken
– Ring: PC or NIC broken
– Star (hub, concentrator, MAU (multistation
access unit, repeater, switching hub): single
point of failure
Ethernet
• Functionality
– Access method: CSMA/CD
– Logical topology: broadcast
– Physical topology: bus or star
• Ethernet II
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Header (preamble) for synchronizing
Destination & source address (MAC layer address)
Type field for network protocol
Data field
– Frame check sequence (FCS): CRC-32
• IEEE 802.3 replace type field with length field
Media-related Ethernet
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10BaseT
10Base2 (Thinet with RG-58 coax)
10Base5 (thick coaxial cable RG-11)
100BaseT Fast Ethernet with 100-Mbps
– 100BaseTX (2 pair of Category 5 UTP or 1 pair
of Type 1 STP)
– 100BaseT4 (4 pair of Category 3, 4, or 5 UTP)
– 100BaseFX (fiber optic cable)
– Trade off between speed and maximum
network diameter
• Gigabit Ethernet (1000Base-X)
Token Ring
• Functionality
– Access method: token passing
– Logical topology: sequence
– Physical topology: ring or star
• IEEE 802.5
– Starting delimiter alert NIC about token approaching
– Access control field (1 for busy, 0 for free)
– Frame control field indicate regular data or network management
frame
– Destination & source address (MAC layer address)
– Routing information field for multiple token ring LANs
– Data field
– Frame check sequence (FCS): CRC-32
– Ending delimiter (ending or intermediate frame)
– Frame status field for successful delivery
Fiber Distributed Data Interface
• Fiber distributed data interface (FDDI) by
American National standard Institute (ANSI)
• Functionality
– Access method: Modified token passing
– Logical topology: sequential
– Physical topology: dual counter-rotating rings
• Build-in reliability and longer distance
• Single-attachment stations (SAS) or dualattachment stations (DAS)
Fiber Distributed Data Interface
• High speed backbone between LANs
• Primary ring and secondary ring - 100Mbps token
ring
• Fault tolerance
• High-priority station having longer access time
• Maximum 500 stations
• Maximum length of 200 kilometers (rings)
• Maximum 2 kilometers between stations
• Constant data rate for video and voice
Fiber Distributed Data Interface
• Applications
– Campus backbone
– High-bandwidth workgroups (multimedia
application)
– High-bandwidth subworkgroup connection
(servers)
• Hardware: FDDI concentrator or hub,
FDDI/Ethernet bridge
• Media: fiber optic cable or copper distributed data
interface (CDDI) for limited distance (100m)
100VG-AnyLAN
• Ethernet and token ring packets
• Demand priority access (DPA) or demand
priority protocol: round robin polling
scheme
• Priority is assigned by application program
and ports
• Max 4 hubs between two nodes
100VG-AnyLAN
• Hardware: 100VG-AnyLAN hubs arranged
in a hierarchical form
• Media: 4 pair of Category 3, 4, or 5 UTP; 1
pair of Type 1 STP; or single mode and
multimode fiber optic cable
Isochronous Ethernet
• Iso-Ethernet in IEEE802.9a (Isochronous
Ethernet Integrated Services)
• Synchronize all circuits with a single
common clocking reference
• Guaranteed delivery time for voice and
video
• Use ISDN WAN link
Isochronous Ethernet
• 16.144-Mpbs bandwidth
– P channel for Ethernet traffic
– C channel ( B channel and D channel)
• Service Modes
– 10BaseT
– Mutiservice: multimedia
– All-isochronous: real time video or voice
distribution
Isochronous Ethernet
• Hardware:
– hubs: Iso-Ethernet attachment units (AU)
– Workstation with Iso-Ethernet NIC: integrated
service terminal equipment (ISTE)
Wireless
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Transmitter and receiver
100 - 300 feet
Infrared technology (line-of-sight)
Spread spectrum technology (no ling-ofsight)
• Special application
Performance Factors
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Protocol (CSMA/CD, token ring)
Speed of transmission (line)
Amount of traffic
Error rate
Software
Hardware
Selection Process
• Long range thinking, planning and
forecasting
• Selection team
• Checklist of criteria
• Cost & benefit analysis
• Technical alternatives
• Management and Maintenance
Selection Criteria - I
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Number of user
Geographic spread
Applications
Performance
Cost
Security
Wiring
Selection Criteria - II
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Installation
Maintenance
Vendor support and training
Future expansion
Workstations
Compatibility to existing LANs
Interface to other networks
Costs
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Workstations
Servers
Printers
Cabling
Bridges, routers, brouters, gateways
Training
People (consultant, administrator etc.)
Maintenance
Space & Environment
Installation
• Choices
– Suppliers or dealers
– In house
• Tasks (project management)
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Install hardware and software
Test access and capability
Trouble shoot
Document
Train user
Help center
Management & Maintenance
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Organization: LAN administrator
Management: policies and procedures
Documentation
Hardware and software control
Change control
Back up (hardware and software)
Security (logical and physical)
Application (compatibility, integrity, & efficiency)
Performance monitoring
Security
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Password
Sign off
Encryption
Backup
Downloading
Viruses protection
Dial-up access
Legal software
Internal and external auditing
Written policy and procedure
Assignment
• Review chapter 5
• Read chapter 6